Magnetic horn



Jan. 27, 1931. F. F. DORSEY 1,790,004

` MAGNETIC HORN Filed MaICh 25, 1926 Patented Jan. 27, 1931 narran srarss PATENT orrcs rameurs n. noBsnY, or` ROCHESTER, NE'WYORK, AssIGNoR, BY ivrEsNE AssiGNMENrs,

TO NORTH EAST APPLIANGE CORPORATION, OF

RtTION OF NEW YORK MAG-Nerio HORN` Application mediteren z5, 192e. serial No.9?,esa

This invention relates to horns or sound `siginils of the type in which a diaphragm is phragm. It has been found that thecorrect operation of such a horn depends largely upon theieXtent of the air gap between the armature and the magnet, and that for best results it is necessary to adjust this air gap accurately in each horn. The object ot the present invention vis to provide simple, inexpensive and convenient means for accomplishing such adjustment, and to this end it is proposed to use a spacing member interposed between two ot the members of the horn and subject to the application of pressure by means ot a bolt or a screw-threaded. stud, this spacer being so formed that when subjected to suilicient pressure it may/be slightly collapsed or reduced in thickness. so as to permit a change in the normal air gap of the magnetic circuit. v

In the accompanying drawings, Fig. 1 is a side elevation, partly in section, ot a horn embodying the present invention. Fig. 2 is an enlarged detail view, showing the spacing washer, and adjacent parts, as used in Fig. 1. F ig. 3 is a sectional view on the line 3'3 in F ig. 2; and Fig. 4 is a detail View or" a modified form of the invention.

The invention is illustrated as embodied in a horn having a corrugated metal diaphragm 5 which is clamped, at its margin, between a shell or body member 6 and a front plate 7.

A horn-proper or projector1 8 is attached to the front plate in the usual manner. The

' armature is shown as having the form of a metal bar 9, while the magnet vcomprises a central. core 10 surrounded by a winding 11,.

This winding may be energized by an alter-y nating or pulsating current in any convenient manner.

The armature bar 9 is shown as attached to the middle of the diaphragm by means lJ5 of a holt 12, this bolt having a wide head 13 j which constitutes a part of thefmagnetic circuit, and a nut 14 is screwed `on the other en ol the bolt.

The spacer, in which the present invention particularly resides, s shown in Figs. l and 2 actuated by means ot an electro-magnet act-` upon an armature attached to the d1a` as interposed between the diaphragm and the armature. Itis preferably drawn from sheet metal oit' suitable thickness, and has a cuplike general form comprising a short cylindrical portion 15 with a peripheral lange'l. lie diaphragm' is clamped between this flange 16 and a thick Washer 18, these parts being drawn tightly together by the action st the lnut andthe bolt.

inforder to permit the yspacerto be compressed or collapsed for the purpose set forth, its rear end comprises a convexor `dome-like `portion 17 which rests against the armature.

This form is suliciently stiltto permit the parte to be clamped tightly together and to be unyielding normally; but if the nut be turnedwith suliicient force, lthe portion 17 may be more or less flattened, thus permitting theA armature to be vdrawn nearer to the diaphragm, and this Acauses the Vair gap between` the magnet core and the bolt tobe increased.

The parts of the horn are preferably so designed that when the horn is originally assembled the air gap isin all cases somewhat less than'that desired, and the airgap may then be'increased to the necessaryfdegreeby turning the nut and collapsing the spacer as just described. ln order to prevent 'the parts from beingturned out of their `proper position whenthe'nutis turned, the

bolt is vflattened onI two sides, as shown, the'Y openings in the diaphragm, the armature and the washer 18 being formed to correspond.

The compressible spacer is not necessarily interposed between the armature and the dia-- phragm, but it may be used at'any other point where it can atfect the air gap. For eX- ample, as shown in Fig. 4:, it may be interposed between the body shell 6 and the magnet. In this case the magnetic core is pro-` vided with a threaded and flattened shank 19, and a nut 2O is screwed upon the rear end of this shank. By tightening this nut the spacer may be collapsed so as to permit the magnet to move rearwardly and thus in-V crease the air gap.V Y

It will be apparent that as'the convex end ofV the spacer is llattened, thediameter of its area of engagement with the armature or Other part is increased, While ,its resistance to ROCHESTER, NEWYORIL A como;

further deformation is increased, owing to the increasing abruptness in the bend of the metal. For these reasons the spacer tends automatically to preserve the parallel relation of the parts between which it is interposed, since, if the spacer chances to be collapsed more on one side of the axis than the other, the` resistance to further deformationV at that side becomes greater than the resist,- ance at the'opposite'side, and the tendency to unequalv deformation thus corrects itself.

The spacer need not have the precise form and construction shown and described, the essential point being that it be of such .material and such form that it is capable of deformation, but is substantially rigid both before and after such deformation.

The invention claimed is:

l. n a magnetic horn, the combination, with horn members Ycomprising a body and a diaphragm, and with electromagnetic actuating members comprising a magnet and an armature, attached respectively to said horn members, of a spacing membery interposed between one of said horn members and the actuating member which is attached thereto, said spacing-member being in the form of a continuous sheet-metal cup, centrally perforated to receive fastening means, and having a rigid lip and a deformable convex bottoni, and screw-threaded fastening means securing the horn member, actuating member and spacing member rigidly together and adapted, upon the application oi' -sui'iicie-nt force, tosubj ect the spacing member to said abnormal pressure for the purpose of adjustment.

2. ln a magnetic horn, ak spacer, Jfor the purpose described, in the form ci' a continuous sheet-metal cup, centrally perforated to receive fastening means, and having a rigid lip anda deformable convex bottom.

In a magnetic horn, a spacer, for the purpose described, in the form of a sheet- Vmetal cup having a continuous, rigid outwardly-flanged lip and a centrally perforated conveX bottom adapted to be flattened under pressure.

FARNUM F. DORSEY. 

